interesting characteristics for the current project [18, 19]. The most noteworthy general features of this viewer are the following:

1. The viewer has an intuitive interface that is easy for new users to learn and use, which makes it easier to expand the screening model by adding new referring physicians to the system.

2.The viewer is based on an open-source software.

3.The viewer has a customizable code. The main tree of the project is offered in a way that each user can personalize it for speciÞc needs. The ClearCanvas Workstation has customization possible at different levels; for example, we can easily customize the toolbar by adding or deleting favorite physician gadgets from the default list of the viewer. The toolbar allows these conÞgurations without programming interactions. When more complex changes or extra contributions are needed, direct editing of the source code is necessary, which can be achieved by editing the main source code or creating a plug-in that works over the main code. Because ClearCanvas is based on C# programming language, both methods of development require NET knowledge.

4.The product is supported by the wholesaler. Discussion forums are available on the viewerÕs ofÞcial webpage. Anyone can contribute to or help with ideas and problems about the viewer and share programming codes or plugins between developers. Some problems identiÞed during setup of the viewer for ophthalmology were solved thanks to the technical support of ClearCanvas.

5.The viewer has a multimonitor working mode. Working in this mode with several monitors mode accelerates image assessment. The user can divide the patient information and the images into different screens with all data visible simultaneously.

6.An imaging tool is also available. This multipurpose viewer presents some interesting image tools, such as a magnifying glass, zoom capability, thumbnails button, image layout, and spatial locator, among others. This makes it possible to delimitate the most used imaging tools in ophthalmology.

Regarding the DICOM features, the most relevant are the following:

1.The DICOM complies with the existing industry standards, such as DICOM, HL7, and IHE.

2.According to the DICOM standard, the viewer satisÞes image communication aspects related to a PACS, such as query, import, send, and image receiving.

3.Study Þltering is another outstanding characteristic of ClearCanvas. This feature offers the ability to Þlter studies depending on one or more attributes of interest. Thus, specialists can manage the image repository depending on the value of the DICOM attributes of their choice such as patient identiÞcation, modality, date, physicianÕs name, or referring physicianÕs name, among others.

4.The DICOM workstation allows linking of a customized list of attributes to a modality and shows them by default overlayed over the image on the screen. Information needs among specialists from different medical Þelds can differ depending on each oneÕs techniques. This feature allows software adaptation to each specialty. Moreover, to look up the rest of the attributes, this viewer also can display them upon demand.

5.The DICOM offers study anonymity, which is a useful feature when a clinician wants to display a study without compromising patient identity.

6.All DICOM multimedia material can be exported to well-known media formats, such as BMP, GIF, JPG, PNG, TIF, or AVI.

16.4Results

16.4.1 Phase 2: Agreement Evaluation

The four GPs completed all stages of phase 1. After that, the agreement of the evaluation was performed online. The kappa indexes were 80%, 81%, 93%, and 95%, respectively. In the four cases, the conÞdence intervals included 85%. These results were considered adequate to proceed to the next phase.